Hoya Variable Density II ND3-400 Filter

For still images, variable density filters shorten the shutter speed according to the photographer's intentions when the shutter speed cannot be shortened due to camera limitations. When shooting video, it is important that the shutter speed matches the frame rate set. This means that it should be equal to twice the frame rate for best results. By using variable density filters, the shutter speed can be set to the correct value to obtain the natural and smooth movement desired in video recordings, as shown in the following image.